1. Technical Field of the Invention
The present invention relates to telecommunication systems and, more particularly, to an intelligent policy server system and method for providing multiple service policy features or options, and for managing bandwidth usage in an Asynchronous Transfer Mode (ATM) network by enforcing appropriate policy features.
2. Description of Related Art
In telecommunication networks, two types of information must be transmitted between the nodes comprising the network: (i) user payload (e.g., voice, video, or data); and (ii) signaling information to control (e.g., set-up and tear-down) the logical paths carrying the payload. In the current telephone network, for example, the signaling information is carried by a separate network known as the common channel signaling (CCS) network. As an advancement over the CCS networks, it is desirable that the public switched networks be provided as multi-service, multi-protocol networks capable of carrying the signaling information in the same physical network.
Asynchronous transfer mode (ATM), as a networking technology, has been gaining increasing popularity as the desirable fabric for the Broadband Integrated Services Digital Networks (B-ISDN) which provide such diverse services as voice, multimedia, data, imaging, real-time video, video-to-home, et cetera, wherein the signaling information is carried in the same physical network, but over a separate logical connection. ATM technology, which is perceived to be the underlying technology for the high speed networks of the future, is highly scalable in terms of access speeds (ranging from as low as 1.5 Mbps to as high as 1.2 Gbps and more), in terms of geography and topology (Local Area Networks, Wide Area Networks, etc.), and in terms of application traffic.
One characteristic of ATM networks is that they are connection oriented, that is, before two end nodes can communicate they need to establish a connection between them. However, unlike circuit-switched networks (e.g., the Public Switched Telephone Network or PSTN), the connection between the two end points does not consume a fixed bandwidth. Instead, bandwidth is allocated statistically, whereby a large number of connections can share the bandwidth of individual links in the network. That is, the connection is virtual and does not exist physically. Each node in the path decides the route that it will use when information packets begin flowing. Since these connections are not dedicated bandwidth channels, they are commonly referred to as Virtual Channel Connections (VCCs) or Virtual Circuits (VCs), wherein one of the VCs of the individual links may be used for carrying signaling information.
VCCs between two endpoints disposed in an ATM network can be established in one of at least two ways:                By provisioning: These VCCs are called permanent virtual circuits (PVCs) which are established by configuring each network element along the path with the required information to establish an end-to-end VCC.        By signaling: These VCCs are called switched virtual circuits (SVCs) which are established on demand by the communicating end systems using known dynamic protocol messaging.        
In the provisioning method, the virtual circuits are permanently configured and left in place until the subscribers want them to be removed. Typically, no special signaling protocol is required to handle control signaling (i.e., set-up and tear-down) of the PVCs. On the other hand, the SVCs are created and destroyed dynamically as needed and, accordingly, require a signaling protocol for exchanging messages necessary to set up and tear down SVC connections.
Signaling across ATM networks to establish SVCs is broadly divided into two functional parts: (a) signaling between the user equipment and the network at the access; (b) signaling between network elements within the network core. The former is referred to as the User Network Interface (UNI) and the latter is referred to as the Network-Node Interface or Network-Network Interface (NNI).
Due to concerted efforts among several governing bodies, standards have emerged for both UNI and NNI signaling. As is well-known, these standards have facilitated multi-vendor and interoperable network environments in the ATM implementations today, thereby giving rise to service-based market differentiation and segmentation.
Because of the ever-increasing hold of the ATM on today's public and private networks, service providers are being challenged to give their customers various service options such as, for example, guaranteed Quality of Service (QoS) that the customers desire while maximizing the use of the bandwidth in the network. Furthermore, as the ATM networks gain in popularity, issues such as network reliability, resource management, robustness in terms of immunity to malicious attacks, et cetera, have become increasingly significant.